Conventionally, a flight management system of an unmanned aircraft comprises, within said control station, a set of successive navigation functions and, within the aircraft, a control function for the aircraft based on guidance setpoints which are roll, pitch, thrust and speed constraints that the aircraft is assumed to have to observe. The control function drives the aerodynamic equipment of the aircraft (control surfaces, engines) so that it observes the guidance setpoints.
In conventional drone systems, the implementation of all the successive navigation functions hosted by the control station generates guidance setpoints.
The drones are more and more regularly required to cross civilian airspaces to reach their theatre of operations, for training requirements, internal civil safety requirements or for monitoring requirements (forest fires, borders, events, etc.).
Now, for an aircraft to be able to cross a non-segregated airspace, it must be authorized therein. A non-segregated airspace is a space that is reserved neither for civilian applications nor for military applications but which may accommodate both types of applications, unlike a segregated airspace which is dedicated to one of these two applications. Authorization to navigate in a non-segregated airspace entails demonstrating that the aircraft can observe strict safety conditions.
The ICAO (International Civil Aviation Organization) has thus defined the CNS (Communication/Navigation/Monitoring) safety concept which combines, by categories and missions, the systems and procedures on the ground and on board the aircraft that make it possible to achieve the safety objectives. The communication C represents the interchanges between the aircraft and the air traffic control authorities ACT or between an aircraft and its piloting station. The navigation N relates to the location of the aircraft (where am I?), the flight management (where should I go?) and to guidance (how do I go there?). The monitoring aspect S relates to the detection of upcoming obstacles with regard to the landscape, other aircraft, or hazardous weather conditions. A performance characteristics is allocated to each of these key aspects C, N and S, in order to obtain the required safety level. The demonstration that makes it possible to obtain a navigability certificate therefore relies on the C/N/S performance characteristics s and their interactions. In particular, it is essential to demonstrate that the failure of one of the C, N, S components can be compensated for by other components to terminate the flight in safety conditions which are adequate.
Now, the piloting systems for the current drones do not make it possible to observe the safety conditions necessary for inclusion in civilian traffic. For example, in the case of failure of the communication between the piloting station and the drone, the latter cannot continue its mission with adequate safety conditions because it is normally entirely piloted from the ground. The guidance setpoints are generated by implementation of a set of successive navigation functions within the control station. The aircraft itself is not capable of generating guidance setpoints. The drones must therefore observe stringent procedures in order to be able to cross civilian spaces: several days' prior notice, accompanying aeroplanes, closure of civilian traffic for a time period.